Safety device for rock drills



Nov. 29, 1932.

E. B. LEAR SAFETY DEVICE FOR ROCK DRILLS Filed July 2. 1931 Hfs ATTORNEY.

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Patented Nov. 29, 1932 UNITED VSTATES PATENT oFFIcr:

EARL B. LEAR, 0F PHILIVJIPSBURGQVNEW JERSEY, ASSGNOR TO INGERSOLL-RAND COM- P ANY, 0F JERSEY CITY, NEW JERSEY, A COEEGRATON CF NEVI JERSEY i SAFETYVDEVICE ron ROCK niiiLLs Application led July 2,

QThisinvention relates to rock drills, but more particularly to a safety device for fluid actuated rock drills, as for instance, those of the stop'er type having rotation mechanism for-rotating the lworking implement in the drill hole and in whichthe hammer piston of the drill and a rilie bar interlockingly engaged thereby, serve as instrumentalities for rotating the working implement.

One objectof the invention is to enable the rotation mechanism to be rendered promptly 'ineffective upon the occurrence of circumstances in the drill hole which would cause the working implementto become stuck and, in consequence, cause the casing parts of the rock drill to rotate about the working implement. f

Other objects will be in part obvious and in part pointed out hereinafter.

In they drawing accompanying this specik fication and forminga part thereof and in which similar reference characters refer to similar parts,

\ Figure 1 is asectional elevation of so much of a rock drill as will serve to illustrate the invention and a practical application thereof,

Figure 2 isa transverse view talrenthrough Figure l on the line2-2 looking in the direction indicated by the arrows, and

Figure 3 is a transverse view taken through Figure 2 on the linefS-S looking in the direction indicatedby the arrows.

Referring to the drawing, in which ,is shown an intermediate portion of a rock drill of the stoper type, A and B designate the percussive and feeding elements respectively of the drill. n

The percussiveelement comprises theusual cylinder C having a piston chamber D wherein i'sarrang'ed a reciprocatory hammer piston E for actuating the working implement (not shown) but which may extend into and be interlocked with suitable chuck mechanism (not shown). The chuck mechanism may, in turn, be conveniently interlocked with the hammer piston E in a well known manner to effect rotary movement of the working implement in accordance with thedegree of rotative movement of the hammer piston. Y

1931. 'semina saires?.l

The pressure fluid utilized for actuating the piston E may be distributed tothe piston chamber D by a distributing valve such as that designated by F and arranged within a valve chamber G formed in this insta-nce by i a pair of plates H and J at the rear end of the cylinder C. In the arrangement shown, the plate J is disposed between the cylinder C and the plate H and formsa closure for the rear end of the piston chamber D. The rear Vend of the plate J serves as a seating surface K for the wings L and O of the valve F. l

The wing O of the valve in this instance controls the admission of pressure fluid to the rear end of the piston chamber D through a rear inlet passage P in the plate J. The wing L controls the flow of pressure fluid from the valve chamber G through a front inlet passage Q located in the plate J and in the cylinder C to convey pressure fluid to the front end of the piston chamber.

The rotation mechanism employed for iniparting rotary movement to the piston E comprises a ratchet ring R having a bore S to receive the head T of a rifle bar U which eX- tends into the piston chamber D to interlockingly engage the hammer piston E in the usual manner. `Disposed in the head'T to oscillate therein are pawls V, two being shown in the present instance, and said pawls ai'e adapted to engage teeth ,WV in the ratchet ring R. The'pawls V may be provided with the usual springs X disposed in recesses Y in the head T and pressing against the pawls V for actuating said pawls into engagement with the teeth W.

The ratchet ring R is encased by a head block Z which seats against the rear end of the plate H with one end and serves with its other end as a seat'for a cylinder of the feedingelement B. The head block Z also serves as a housing for a throttle valve o which is shown in this instancev as being of the rotary type having a lever al for its manipulatioii. -The throttle valve c has a central chamber e into which pressure fluid may be constantly admitted from a suitable source of supply and in the wall of the throttle valve c are a series of ports f, g and 7L. The port la is adapted to register with a supply passage j in the head block Z and the plate H and leading to the valve chamber G, and the port may register with a passage 73 in the head block and opening into the cylinder b.

In addition to the cylinder Z) the feeding element used for advancing the rock drill towards the work in accordance with the penetration of the working implement into the work comprises a feed piston of a well known type which may be provided with a rod p carrying at its lower or outermost end a pointer (not shown) but which may be adapted to seat upon a mine floor to support the drilling mechanism. The feeding cylinder b andthe piston 0 may be of any well known construction in which the piston and cylinder are freely rotatable with respect to each other.

In accordance with the practice of the invention, means are provided for selectively rendering the ratchetl ring R ineffective as an abutment for the pawls V when, owing to accidental circumstances in the drill hole the working implement tends to stick therein. rEhe ratchet ring R is accordingly provided at its front and rear ends with annular flanges Q' and r respectively which seatloosely in annular grooves s and t in the plate H and in the head block Z in such wise that, in the absence of suitable restraining means, the ratchet ring may be rotated freely within said grooves.

@n the outer peripheral surface of the ratchet ring R are a series of longitudinal eX- tending teeth u similar in all essential respects to the teeth 1V to seat against a latch member fu mounted pivotally on a pin w. rEhe latch fv is disposed in a recess a" in the head block Z, and the ends of the pivot pin en are seated in the plate H and the head block Z.

T he latch o comprises a dog or pawl y having an end surface a suitably shaped to conform to the side surfaces of the teeth a which it is intended to engage. On the opposite side of the pin w and integral with the pa-wl y is a wing 2 against one side of which acts a spring-pressed plunger 3 seated in a recess 4 in the head block .Z to normally maintain the pawl g/ in engagement with a tooth u.

The arrangement is such that, owing to the pressure exerted against the wing 2 by the spring-pressed plunger 3, the pawl jz/ will be normally maintained in engagement or in position for engaging one of the teeth u. The pawl 1el may thus act as an abutment for the ratchet ring R to counteract the thrust of the pawls V against the ratchet ring R during a stroke of the piston, preferably during the rearward stroke and during which time the working implement is being rotated in the drill hole to change its position between successive blows of the hammer piston E thereagainst.

Means are provided for actuating the latch o out of engagement from the teeth u. To this end the head block Z is provided with a chamber 5 to receive the head 6 of a plunger 7 acting against the wing 2 of the latch v and counter to the spring-pressed plunger 3. rl`he free end of the head 6 constitutes a pressure area 8 against which pressure [luid may act for actuating the plunger 7 in the direction of the wing 2, Such pressure fluid may be conveyed into the chamber 5 by a passage 9 in the head block Z and wherewith the port g in the throttle valve c is intended to register.

Opening into the same end of the chamber 5 as the passage 9 is an atmospheric vent 10 which extends through the head block, the plates H and J, the cylinder C and a rotation handle 11 which may, as indicated, be secured to the cylinder C. The portion of the passage 10 located in the rotation handle `11 opens into a bore 12 in the rotation handle.

Disposed within the bore 12 is a guide bushing 13 which is retained fixedly inoperative position in the bore 12 by a plug 11i threaded into the outer end of the bore 12. The guide bushing 13 has a bore 15 to slidably receive a stem 16 of a valve 17 of the poppet type which is adapted to seat on a bevelled surface or seat 18 in the bushing 13.

ln the innermost end of the bushing 13 is a hollow plug 19 which serves as a seat for a spring 2O acting against the valve 17 to press said valve to the seat 18. The portion 21 of the bore adjacent the valve seat 18 is preferably enlarged so that when the valve 17 is in the open position pressure fluid flowing from the passage 10 through the hollow plug 19 into a chamber 22 wherein the spring 2O and the valve 17 are located may pass readily through the enlarged portion 21 to radial ports 23 in the bushing 13.

The radial ports 23 open with their outer ends into an annular groove 2a in the periphery of the bushing 13. The groove 24 in turn communicates with a passage 25 which extends through a depending grip portion 26 on the rotation handle 11 and which grip p0rtion is intended to be grasped by the operator to hold the casing elements of the rock drill immovable and unaffected by the thrust imparted by the rotation mechanism of the drill.

Disposed on the outer end of the stem 16 of the valve 17 is a button 27 which, as will be observed, is in close proximity to the grip portion 26 so that it may be Within easy reach of the hand whereby the grip portion 26 is grasped.

rlhe operation of the device is as follows. lVith the throttle valve c in the open posi.- tion, pressure fluid flows into the feeding ovlinder b and the valve chamber Gr in the chamber 5 wherein the head 8 of the plunger 7 is located. The pressure fluid admitted into the feeding cylinder will act against the piston 0 and will move the drilling apparatus toward the work in a well known manner to constantly maintain the piston E in such position with respect to the working implement as to assure an effective application of the blows of said piston to the working implement. v

The pressure fluid admitted into the valve chamber G is distributed to the ends of the piston chamber D by the distributing valve F. Upon each admission of Huid into the rear end of the piston chamber D, the piston E is actuated forwardly against the working implement, and upon the reversal of the valve F pressure fluid is admitted into the front end of the piston chamber D to return the piston.

During such operation of the drilling apparatus and with the working implement capable of free rotation in the drill hole, the rifle barrU may rotate freely relatively to the ratchet ring R since, during the forward stroke of the piston E, the pawls V will merely pass over the teeth W. The piston E is therefore capable of delivering heavy blows of impact against the working implement.

Upon the return stroke of the piston E the pawls V will be pressed into engagement with the teeth W by the springs X. The piston E will then describe a partial revolution and,- being suitably interlocked with the working implement, the working implement will also be rotated to change its position in the drill hole for a succeeding blow of the hammer piston.

This operation of the hammer piston and the rotation mechanism may continue indefinitely as long as the working implement remains free to rotate within the drilly hole. The rotation ratchet R will then be constantly maintained against rotative movement by the latch 'U and the latch o in turn is held in this engaging position by the spring-pressed plunger 3.

During such operation, and which may be said to be the normal operation, the valve 17 is maintained in the open position by applying pressure against the button 27 so that the pressure fluid iowing into the chamber 5 may readily escape through the passages connecting the chamber 5 with the passage 25. The spring-pressed plunger 3 will therefore be unopposed. Y

In the event, however, that owing to breakage of the working implement or, as at times happens, the working implement enters a crevice in the rock and becomes stuck therein so that a thrust of sufficient force is imwill be released so that it may merely rotate with the rifie bar.

The casing elements of the drill will thereafter remain entirely stationary and in this way is avoided the danger of inflicting severe injury to the operator, such as is frequently caused by the rapidly rotating projecting parts ofthe rock drill.

After the working implement has again been freedor replaced the valve 17 may again be opened to exhaust the pressure fluid from the chamber 5, whereupon the spring-pressed plunger 3 will again actuate the latch 'v into engagement with the ratchet ring R which will then be held immovable to serve as a fixed abutment for the pawls V.

I claim:

In a safety device, the combination with a rock drill having a hammor piston and rotation mechanism for the piston comprising a rifle bar wherewith said piston is slidably interlocked, a pawl carried by the rifle bar, of a ratchet ring to serve as an abutment for the pawl and being rotatable with respect to the rifle bar, a locking device for the ratchet ring, a plunger for actuating the locking device out of engagement from the ratchet ring, a pressure area on the plunger and being in constant communication with a source of pressure fluid supply, an atmospheric vent for the pressure area, valve means to control the vent and being normally held open to afford communication between the pressure area and the atmosphere, and means to close the valve means upon release thereof, thereby entrapping pressure'fluid inthe vent to act against the pressure area for releasing the locking device from the ratchet ring.

In testimony whereof I have signed this specification.

EARL B. LEAR.

parted to the rock drill to jar the rotation handle out of the operators hand the spring 20 will immediately act to close the valve 17. The pressure fluid thereafter flowing into the chamber 5 will promptly actuate the plunger 7 vwhich in turn will trip the latch u out of engagement from the ratchet ring R and, although the piston E may thereafter con- '1- tinue its reciprocations, the ratchet ring R 

